Studies in mineralization of aqueous aniline using Fenton and wet oxidation (FENTWO) as a hybrid process

A hybrid process for mineralization of aqueous aniline using Fenton and wet oxidation (FENTWO) is studied. It is important to have maximum conversion of ‘N’ atoms from the waste to N₂. The conversion of input ‘N’ atoms in aniline to N₂ was 15% during wet oxidation without the Fenton process and was improved to 50% with the Fenton process. Therefore, a hybrid process of Fenton followed by wet oxidation was studied for mineralization of the aqueous aniline stream. The parameters for the Fenton process were optimized (pH, catalyst, H₂O₂ to catalyst (FeSO₄) ratio, quantity of H₂O₂). The waste obtained after the Fenton process was then treated by wet oxidation for mineralization by having homogeneous CuSO₄ as the catalyst by keeping FeSO₄ therein. This combined catalyst was found to be more effective for the degradation of the intermediates formed in the Fenton process. Wet oxidation (WO) was studied in the temperature range 473–513 K and the oxygen partial pressure range 0.345–1.38 MPa at pH 6.5. The kinetic data was modeled using a power law rate expression in terms of chemical oxygen demand (COD). The optimum temperature for formation of more N₂ gas was found to be 493 K. The treated waste stream was found to contain oxalic acid using HPLC, and NH₄⁺, NO₃^? and NO₂^? ions using ion chromatography analysis. Copyright © 2007 Society of Chemical Industry